The liquefaction of industrial gas is a power intensive operation. Typically the industrial gas is liquefied by indirect heat exchange with a refrigerant. Such a system, while working well for providing refrigeration over a relatively small temperature range from ambient, is not as efficient when refrigeration over a large temperature range, such as from ambient to a cryogenic temperature, is required. This inefficiency may be addressed by using more than one refrigeration circuit to get to the requisite cryogenic condensing temperature. However, such systems will require a significant power input in order to achieve the desired results.
Accordingly, it is an object of this invention to provide a multiple circuit arrangement whereby industrial gas may be brought from ambient temperature to a colder temperature, especially to a cryogenic liquefaction temperature, which operates with greater efficiency than heretofore available multiple circuit systems.